The senior patent holder is presumably now Ford Oxaal, who discusses
his licensing policy, his relationship to iPIX, and the status of
Helmut Dersch's "PT toolset" at
http://www.pictosphere.com/kwx/faq.html .
I have made no attempt to evaluate the strength of his patents in
light of the prior art, nor whether his patents are the only ones that
might be enforced against the PT tools; but there is at least some
indication that Oxaal has estopped himself against enforcing his
patents against non-commercial use of whatever software components are
part of "PT-Viewer". If his patents have any traction against
libpano12, then it presumably cannot go into main, but may be suitable
for non-free.
Cheers,
- Michael
(IANADD, IANAL, TINLA)